Investigation of a Potential Cotumorigenic Effect of the Dioxides of Nitrogen and Sulfur, and of Diesel-Engine Exhaust, on the Respiratory Tract of Syrian Golden Hamsters Uwe Heinrich, Ulrich Mohr, Rainer Fuhst, and Carsten Brockmeyer FraunhoJer Institute for Toxicology and Aerosol Research, Hannover, Federal Republic of Germany Includes the Report of the Institute's Health Review Committee Research Report Number 26 The Health Effects Institute (HEI) is a nonprofit corporation founded in 1980 to assure that objective, credible, high-quality scientific studies are conducted on the potential human health effects of motor vehicle emissions. Funded equally by the U.S. Environmental Protection Agency (EPA) and 27 automotive manufacturers or marketers in the United States, HEI is independently governed. 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Cuozzo Accounting Assistant Research Agreement No. 83-26 Copyright © 1989 by Health Effects Institute Printed at Capital City Press, Montpelier, VT TABLE OF CONTENTS Research Report No. 26 Investigation of a Potential Cotumorigenic Effect ofthe Dioxides of Nitrogen and Sulfur, and of Diesel~Engine Exhaust, on the Respiratory Tract of Syrian Golden Hamsters INVESTIG!:..TOR..<i' REPORT Uwe Heinrich, Ulrich Mohr, Rainer Fuhst, and Carsten Brockmeyer Abstract . 1 Larynx and Trachea . 7 Introduction . 1 Lungs ................................. 13 Aiins............ 2 Histopathological Findings in the Respiratory Tract Materials and Methods . 2 of Animals Not Assigned to Serial Sacrifice .... 14 Animals and Housing Conditions . 2 Nasal Cavity ............................ 14 Diesel-Exhaust Exposure . 3 Larynx, Trachea, and Major Bronchi ........ 14 Exposure to a Nitrogen Dioxide/Sulfur Dioxide Lungs ................................. 15 Mixture.................................. 3 Tumors in the Respiratory Tract ................ 15 Diethylnitrosamine Treatment. 5 Discussion . 17 Histopathology . 5 Conclusions ................................... 20 Statistical Analysis . 6 Acknowledgments .............................. 22 Results . 6 References .................................... 22 Health Status of the Animals . 6 Appendix A. Cumulative Proportion of Surviving Survival Time . 6 Animals and Animals Dying Without a Respiratory Tract Tumor ...................... 24 Histopathological and Scanning Electron Microscopy Findings in the Respiratory Tract About the Authors .............................. 27 Abbreviations After Various Exposures to N02/S02 Gas or .................................. 27 Diesel Exhaust . 6 HEALTH REVIEW COMMITTEE'S REPORT Health Effects Institute Introduction ................................... 29 Attainment of Study Objectives ................. 32 The Clean Air Act .............................. 29 Methods and Study Design .................... 32 Background ................................... 29 Results and Interpretation ..................... 32 Justification for the Study ........................ 31 Remaining Uncertainties and Implications for Objectives of the Study. 31 Future Research . 33 Study Design .................................. 31 Conclusions ................................... 33 Technical Evaluation ............................ 32 References . 33 j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j J INVESTIGATORS' REPORT Investiga~ion of a .Potential Cotumorigenk Effect of the Dioxides of Nitrogen and Sulfur, and of D1esel~Engme Exhaust, on the Respiratory Tract of Syrian Golden Hamsters Uwe Heinrich, Ulrich Mohr, Rainer Fuhst, and Carsten Brockmeyer1 ABSTRACT oxidants, and polycyclic aromatic hydrocarbons (PAHs), are actually common to all kinds of combustion-engine ex­ haust. In addition to these traces, however, Syrian golden hamsters (480 males and 480 females) allo­ diesel engines characteristically produce and discharge carbonaceous cated into 24 groups were exposed 19 hours per day and 5 particles and, to a small extent depending days per week for 6, 10.5, 15, or 18 months to total diesel ex­ on the quality of the fuel, sulfur dioxide ). haust, diesel exhaust without particles, a mixture of nitro­ (S02 Some of the less volatile PAHs are known carcinogens and adsorb easily, along with gen dioxide (5 parts per million [ppm] 2) and sulfur dioxide other vaporized organics of low volatility, (10 ppm), or clean air. Two exposure groups from each test on the surface of the diesel soot particles. There are suggestions atmosphere were also treated by a single subcutaneous in­ from trends in epidemiologic investigations (Howe eta!. 1983) jection of either 3 mg or 6 mg of diethylnitrosamine/kg of and indi­ cations from laboratory body weight to evaluate an enhancing effect of diethyl­ experiments (Heinrich eta!. 1982, 1986; Brightwell eta!. 1986; nitrosamine on exposure-related changes. Morphological Ishinishi eta!. 1986; Iwai eta!. 1986; Mauderly et a!. 1986) that exposure evaluation was done by histopathology. Minor changes of to diesel soot might increase the risk of lung cancer the larynx and trachea were investigated by scanning elec­ in humans. Recently, long-term inhalation studies on rats have tron microscopy, which showed a loss of ciliated cells in all shown that diesel­ engine exhaust, if exhaust-exposed groups. After exposure to diesel exhaust inhaled in sufficiently high concentra­ tions, induces lung tumors (bronchioloalveolar adenomas, with or without particles, focal metaplasia and dysplasia of adenocarcinomas, and squamous the respiratory epithelium were seen in the oldest animals cell tumors) in rats, but not in hamsters (Brightwell et 1986; by scanning electron microscopy. In the same specimens, a!. Heinrich et a!. 1986). attached mucous droplets indicated changes in mucous cells and mucous viscosity. These hamster results confirmed findings of an earlier long-term inhalation study (Heinrich eta!. 1982) in which Only the exposure to total diesel exhaust significantly in­ we did not observe any carcinogenic effects of diesel creased the tumor rate in the upper respiratory tract of male ex­ haust in Syrian golden hamsters; only female Syrian hamsters treated with 6 mg of diethylnitrosamine per kg of golden hamsters were